Pressure gas operated electrical switch with two stationary main contacts and a movable bridging contact basket



3,264,439 TATIONARY E BRIDGING CONTACT BASKET 5 Shae ts-Sneet 1 Aug. 2, 1966 J. ERNSTING PRESSURE GAS OPERATED ELECTRICAL SWITCH WITH TWO 5 MAIN CONTACTS AND A MOVABL Filed July 18, 1963 INVENTOR Ju'rge m Ernst/n3 BY 1% M JJLWM I Pm AYTTORNEYS Aug. 2, 1966 J. ERNSTING 3,264,439

ELECTRICAL SWITCH WITH TWO STATIONA ACTS AND A MOVABLE BRIDGING CONTACT BASKET 5 Sheets-$neet 2 PRESSURE GAS OPERATED MAIN CONT Filed July 18, 1963 INVENTOR JU r en Ernsimg BY W X7Pz/Jam W I ZATTORNEKS Aug. 2, 1966 ERNSTING J 3,26 39 PRESSURE GAS OPERATED ELECTRICAL SWITCH WITH TWO STATION, Y MAIN CONTACTS AND A MOVABLE BRIDGING CONTACT BASKET Filed July 18, 1963 5 Sheets-Sneet 3 Ago 1.4 Q 77 y QW 7 W 5 a: 6

f a J I A INVENTOR JUr er; Ernst/H5 JOMWJ ATTORNEKS United States Patent 3,264,439 PRESSURE GAS OPERATED ELECTRICAL SWITCH WITH TWO STATIONARY MAIN CONTACTS ANI) A MOVABLE BRIDGING CONTACT BASKET Jiirgen Ernsting, Umiken, Aargau, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Filed July 18, 1963, Ser. No. 295,924 Claims priority, application Switzerland, July 26, 1962, 3,955 62 2 Claims. (Cl. 200148) The present invention relates to a pressure gas operated electrical switch which comprises two stationary spaced apart main contact members and a movable bridging contact basket with contact fingers arranged within a switching chamber, the contact basket being associated with a piston type driving member therefor for driving the basket in such direction as to effect disengagement between the basket and one of the stationary contact members when pressurized gas is introduced into the switching chamber, and there being a loading spring cooperative with the contact basket for returning the same into a bridging contact with both of the stationary main contact members when the pressurized gas fiow into the switching chamber is cut off. A compressed gas switch ha become known where a movable switch pin and a fixed tubular nozzle forming the counter-contact are connected by a movable bridging contact. The latter is connected with a' drive piston and is pushed back onto the tubular nozzle by the compressed gas flowing into the switching chamber during disconnection, while at the same time the switch pin is moved by the drive in the opposite direction. With this arrangement it is disadvantageous, on the one hand, that a separate drive device is needed for the movement of the switch pin and on the other hand, since a simultaneous lifiting of all individual contact fingers off the switch pin does not take place because of the always existing manufacturing tolerances, as well as due to the irregular burning occurring during operation at the individual contact fingers, there results an unfavorable load on the contact finger which last leaves the contact pin. Due to the fact that the latter carries the full disconnecting current in the end, there i formed at its point of contact with the fixed nozzle pipe, due to the electrodynamic action of the current, a very great contact-lifting force and hence, damage to the contacts by the are not subjected to blowing at the lift point. To compensate this, very strong contact pressure springs would be necessary, which, however, would lead to an uneconomical solution.

The object of the present invention is to provide a simple solution where the mentioned disadvantages are avoided, the new arrangement being applicable to advantage for switche up to the greatest disconnecting cur- I rents. According to the invention, it is proposed that at least one of the contact fingers, but not all of such fingers, be designed as a burn off finger, at which the contact between the bridging contact and the fixed pin-shaped contact is eliminated last during a disconnection operation, the current conduction to the burn-off finger being designed as conductor loop in such manner that during engagement, the contact pressure i increased and later the arc is moved toward the center of the tubular nozzle.

Some examples of construction, with reference to which the inventive idea is explained in greater detail, are given in the accompanying drawings.

FIG. 1 shows, partly in section, an example of construction of the switching chamber of a compressed gas switch according to the invention.

FIG. 2 shows another example of construction where the current conduction to the burn-off finger is designed as insulated conductor loop.

FIG. 3 shows, partly in section, the elevation of a switching chamber with burn-01f fingers designed as multiple parts.

FIG. 4 shows a plan cross-section of the switching chamber according to FIG. 3.

FIG. 5 illustrates on a larger scale in perspective a multi-part burn-oft finger as contained in FIGS. 3 and 4.

FIG. 6 shows, partly in section, a switching chamber where the contact fingers or laminations transfer the current to the connected part.

With reference now to FIG. 1, the fixed pin-shaped contact is designated by 1. It is connected through the ribs 2 with a ring part 3 and is held by the latter in the switching chamber housing. The switching chamber housing 4 consists of insulating material and is firmly connected at its upper side with a cylindrical connector part 5, which in turn is firmly inserted in the insert piece 6. The insert piece 6 carries internally the fixed tube 7, which is fitted on its underside with the nozzle mouthpiece 8 consisting of are proof material, which is firmly connected, for example, by soldering, with the screw insert 9. In the switching chamber housing 4 and in part also in the connector part 5, the bridging contact is guided slidingly. It is formed by the contact basket 10 of insulating material which in turn contains the contact laminations 11 and the burn-off finger 12. To produce the contact pressure, parts 11 and 12 rest against the leaf springs 13 in the cont-act basket 10. At its contact surface with the contact pin 1, the burn-oft finger 12 is covered with arcproof material 12a. In like manner, the contact pin 1 has at its upper side a burn-off hood 1a. Between the cams 10a of the contact basket 10, which cams protrude through corresponding slot in the cylindrical insert piece 6, and the nozzle tube 7 there is the return spring 14. The connector part 5 is provided with an aperture 5a, while 5b indicate the connector lug to which the outer connection is connected in known manner. In the figure the contact basket 10 is shown in an intermediate position, where the contact laminations or fingers 11 have already left the contact 1, while the burn-off finger 12 is still in electrical connection with the contact pin 1 by its covering 12a and the burn-off hood 1a. The current path prevailing at this moment is indicated by the winding dash-dot line with arrows. For this purpose the burn-off finger 12 is so oriented within the contact basket 10 that it is always on the side of the connection lug 5b.

The manner of operation of the arrangement is as follows: In the electrically connected position of contact members 1 and 7 the switching chamber is pressureless, the contact basket 10 being in its lower limit position and bridging the nozzle and pin-shaped contacts as a result of the action of the return spring 14. The lower position of basket 10 which then surrounds the upper end portion of the pin-shaped contact 1 is determined by the striking of the slanting lower edge of the basket cams 10a against the slanting upper edge of the mouthpiece 8. The contact laminations or fingers 11 then embrace the contact 1 at its cylindrical part. The current path is formed by parts 5b, 5, 6, 11 and 1.

For disconnection, compressed gas is supplied to the switching chamber from below through the annular channel formed between cylindrical parts 1 and 4. The devices needed for this, of a kind known in themselves, such as a compressed gas tank and switching valve, have been omitted in the drawing for greater clarity, especially as they are not required for comprehension of the invention. By the infiowing compressed gas, the contact basket 10 acting as piston is moved upward counter to the force of the return spring 14, as the space above the contact basket 10 communicates with the atmosphere through the aperture 5a and thus is pressureless. In the position of the contact basket shown in the drawing, the contact between the contact pin 1 and the fingers 11 is eliminated, so that the remaining burn-off finger 12 alone carries'the disconnecting current, a lifting off of the burn-off finger 12 at its point of contact with the insert piece 6 being avoided due to the current loop indicated in dash-dot lines by the action of electrodynamic force, in that the repelling forces between the opposing current paths in parts 5 and 12 cause an intensification of the contact pressure. These same repelling forces bring about also a rapid downward movement of the disconnecting arc to the center of the nozzle tube 7 as soon as the arc is drawn between the burn-off finger 12,

12a and the contact'l, 1a during the further upward movement of the contact basket 10. Then the disconnecting are blown by the compressed gas burns for a short time until its extinction between the contact 1 and the nozzle tube 7, with formation of the arc roots at the burn-off parts In and 8 respectively.

After extinction of the arc, the compressed gas supply is cut off by means of the switching valve not shown, as

- soon as the voltage insulation of the disconnected switch has been taken over in known manner by an isolating voltage switch-point which is connected in series with rangement is that the return spring 14 need not be made i of anti-magnetic material since according to the invention it does not surround the current path, so that harmful heating due to eddy currents cannot occur in the spring. In the vicinity of the upper limit position of the contactbasket 10, a compression attenuation of the moving parts becomes operative as soon as the space above the contact basket 10 is closed off from the atmosphere after the aperture 5a to atmosphere has been passed and thus closed off. Connection of the switch contacts is effected in known manner by closing the mentioned series arranged knife switch, since the power switch point is again closed in the stationary disconnected position of the switch, in that the bridging contact has been brought by the return spring 14 into its lower limit position after stopping of the compressed gas supply.

In FIG. 2 another example of construction is illustrated, the parts corresponding to those of FIG. 1 being marked with the same reference symbols. Here, however, the connector part 5 is so designed that it is inmediate insulating layer 18. In tangential direction, the

width of the yoke 19 is adapted to that of the respective burn-01f finger 12. When several, e.g. two to three, burn-off fingers are present, each has a separate yoke 19 assigned to it, these being possibly also separated from 'each other by intermediate insulating layers. The return spring 14 is arranged in this construction above the connector part 5 and takes support, on the one hand, against the upper collar of the tube 17 and, on the other hand, over the ring 16 and several stay bolts fastened in the contact basket 10, against the latter. The mechanism of action of the arrangement according to FIG. 2 fully corresponds to that as described under FIG. 1. By the yokes 19 embedded insulatingly in the connector part 5 an advantageous concentration of the current paths of the conductor loop is brought about and thereby the contact lifting of the one or more burn-off fingers 12 during the disconnectingoperation is prevented in greater degree. Here also the return spring 14 is so arranged that encirclement of the current path is avoided.

Another example of construction is illustrated in FIGURES 3 and 4. The arrangement shown here is particularly advantageous for switches having great load current disconnecting capacity. By 1, 1a is designated the pin-shaped contact, whose attachment in the switching chamber housing 4 is effected in the same manner by means of parts 2, 3 as in FIGS. 1 and 2. The connector part 5 is of substantially cylindrical design and carries at the top the insert piece 20, into which the nozzle tube 7 is screwed. The contact basket 10 has corresponding recesses for the contact laminations or fingers 11, which apply at the bottom against the contact 1 and at the top against the connector part 5, the leaf springs 13a, 1317 establishing the contact pressure in the connected position. As is evident from the plan cross-section of FIG. 4, there are eight contact laminations or fingers 11 in all. Opposite them are three multi-part burn-01f fingers, each consisting of a hammer-like part 12, 12a and two parts 12b. The mutual engagement of the finger parts is readily visible from FIG. 5. Parts 12 and 12b have between them leaf springs 130 (FIG. 3) to produce the contact pressure which rest, for example, against the finger parts 12b with interposition of a thin insulating layer. The latter can be dispensed with if the leaf springs 130 are provided with an insulating coating. Owing to the fact that the finger parts 12b rest on the connector part 5, while the finger parts 12, 12a rest on the contact pin 1, In, there results the current loop indicated by the dash-dot line with arrows. For the rest, the mechanism of action of the arrangement fully corresponds to that as described in FIG. 1. Due to the antiparallel and closely opposite current paths in the finger parts 12 and 12b there results, upon disconnection of great currents, a particularly effective contact pressure increase at the transition points between the finger parts 12 and 12b on the one hand, and between the finger parts 12b and the connector part 5, on the other. As is evident from FIG. 4, several burn-off fingers 12, 12b may be provided, whereby a favorable current distribution can be achieved. In the chosen example of construction, a total of three-multi-part burn-01f fingers is provided. They are arranged inside the contact basket 10 in such a way that they are always on the side facing the connector flange 5b.

FIG. 6 shows another example of construction where the slidable bridging contact is designed, according to the invention, to increase the dynamic strength, in such manner that a particularly advantageous pressure increase in the connected position is achieved. For this the contact laminations or fingers 11 have a crowned surface 11a, by which, under the axial force of the return spring 14, they apply against the conical inner surface of the connector part 5. By the lug part 11b they rest in a recess of the contact basket 10, so that they can execute a small rolling-sliding movement during connection and are then clamped in the manner of a wedging effect, with the result of a multiplication of the contact pressure corresponding to the inclination of the wedge surface. The inner portion of the connector part 5 may advantageously consist of an inserted bushing 5c of highly conductive material.

I claim:

1. In a pressure gas operated electrical switch, the combination comprising a pair of co-axially aligned main contact members arranged with their ends in confronting spaced relation within a switching chamber to which a pressurized gas is introduced during electrical disconnection of said main contact members, one of said main contact members being in the form of a nozzled tubular from the other main contact member, said bridging contact assembly being comprised of a contact basket of electrically insulating material in which a circular array of contact fingers are located, said basket serving also as a piston which is slidably actuated upon introduction of pressurized gas into said switching chamber thereby to disengage said contact fingers from said other main contact member, a loading spring for said contact basket to return the same to a position wherein said contact fingers re-engage said other main contact member when the pressurized gas flow to said switching chamber is cut off, an electrically conductive cylindrical connector member surrounding said contact basket and forming a cylinder for the sliding movement thereof, said connector member also including a laterally extending lug to which one electrical connection is made to the switch, at least one of only those contact fingers located at the same side of said cylindrical connector member as is located said connection lug being longer than the remaining contact fingers thereby to serve as the last to disengage from said other main contact member, and said cylindrical connector member also including an inverted U-shaped yoke of highly conductive material embedded therein at the side on which said connection lug is located and which surrounds said longer contact finger, said yoke serving in part to establish two closely parallel current fiow paths of opposite direction between said connection lug and the adjacent side of said cylindrical connector member and said other main contact member subsequent to disengagement of said remaining contact fingers but prior to disengagement of said longer contact finger, one of said current flow paths being through said longer contact finger thereby to establish thereon an electrodynami-cally derived force acting in a radially inward direction to increase the pressure of said longer contact finger on said other main contact member and thereafter move the contact disconnection arc toward the center of said nozzled tubular contact member' 2. In a pressure gas operated electrical switch, the combination comprising a pair of co-axially aligned main contact members arranged with their ends in confronting spaced relation within a switching chamber to which a pressurized gas is introduced during electrical disconnection of said main contact members, one of said main contact members being in the form of a nozzled tubular member through which the pressurized gas flows during a contact disconnection, a movable bridging contact assembly arranged for sliding movement upon said tubular nozzled contact member to engage and be disengaged from the other main contact member, said bridging contact assembly being comprised of a contact basket of electrically insulating material in which a circular array of contact fingers are located, said basket serving also as a piston which is slidably actuated upon introduction of pressurized gas into said switching chamber thereby to disengage said contact fingers from said other main contact member, a loading spring for said contact basket to return the same to a position wherein said contact fingers re-engage said other main contact member when the pressurized gas flow to said switching chamber is cut off, said loading spring surrounding said nozzled tubular contact member Within an electrically conductive cylindrical sleeve provided with longitudinally extending slots, an electrically conductive cylindrical connector member surrounding said contact basket and in radial spaced relation to said cylindrical sleeve, the annular space between said cylindrical sleeve and said cylindrical connector member forming a cylinder within which said contact basket slides and with said contact fingers in contact with said cylindrical sleeve, said contact basket including radially inward portions extending through said slots in said cylindrical sleeve and which are engaged by one end of said loading spring, said connector member also including a laterally extending lug to which one electrical connection is made to the switch, at least one of only those contact fingers located at the same side of said cylindrical connector member as is located said connection lug being longer than the remaining contact fingers thereby to serve as the last to disengage from said other main contact member, and means establishing two closely parallel current flow paths of opposite direction between said connection lug and the adjacent side of said cylindrical connector member and said other main contact member subsequent to disengagement of said remaining contact fingers but prior to disengagement of said longer contact finger, one of said current flow paths being through said cylindrical sleeve and thence through said longer contact finger thereby to establish thereon an electrodynamically derived force acting in a radially inward direction to increase the pressure of said longer contact finger on said other main contact member and thereafter move the contact disconnection arc toward the center of said nozzled tubular contact member.

References Cited by the Examiner UNITED STATES PATENTS 2,636,961 4/1953 Schneider 200-148 2,937,256 5/1960 Baltensperger 200-148 3,076,080 1/1963 Ramrath 200150 3,128,360 4/1964 Rietz 200150 FOREIGN PATENTS 175,730 6/1961 Sweden.

ROBERT K. SCHAEFER, Primary Examiner.

BERNARD A. GILHEANY, KATHLEEN H. CLAFFY,

Examiners, P. E. CRAWFORD, Assistant Examiner, 

1. IN A PRESSURE GAS OPERATED ELECTRICAL SWITCH, THE COMBINATION COMPRISING A PAIR OF CO-AXIALLY ALIGNED MAIN CONTACT MEMBERS ARRANGED WITH THEIR ENDS IN CONFRONTING SPACED RELATION WITHIN A SWITCHNG CHAMBER TO WHICH A PRESSURIZED GAS IS INTRODUCED DURING ELECTRICAL DISCONNECTION OF SAID MAIN CONTACT MEMBERS, ONE OF SAID MAIN CONTACT MEMBERS BEING IN THE FORM OF A NOZZLED TUBULAR MEMBER THROUGH WHICH THE PRESSURIZED GAS FLOWS DURING A CONTACT DISCONNECTION, A MOVABLE BRIDGING CONTACT ASSEMBLY ARRANGED FOR SLIDING MOVEMENT UPON SAID TUBULAR NOZZLED CONTACT MEMBER TO ENGAGE AND BE DISENGAGED FROM THE OTHER MAIN CONTACT MEMBER, SAID BRIDGING CONTACT ASSEMBLY BEING COMPRISED OF A CONTACT BASKET OF ELECTRICALLY INSULATING MATERIAL IN WHICH A CIRCULAR ARRAY OF CONTACT FINGERS ARE LOCATED, SAID BASKET SERVING ALSO AS A PISTON WHICH IS SLIDABLY ACTUATED UPON INTRODUCTION OF PRESSURIZED GAS INTO SAID SWITCHING CHAMBER THEREBY TO DISENGAGE SAID CONTACT FINGERS FROM SAID OTHER MAIN CONTACT MEMBER, A LOADING SPRING FOR SAID CONTACT BASKET TO RETURN THE SAME TO A POSITION WHEREIN SAID CONTACT FINGERS RE-ENGAGE SAID OTHER MAIN CONTACT MEMBER WHEN THE PRESSURIZED GAS FLOW TO SAID SWITCHING CHAMBER IS CUT OFF, AN ELECTRICALLY CONDUCTIVE CYLINDRICAL CONNECTOR MEMBER SURROUNDING SAID CONTACT BASKET AND FORMING A CYLINDER FOR THE SLIDING MOVEMENT THEREOF, SAID CONNECTOR MEMBER ASLO INCLUDING A LATERALLY EXTENDING LUG TO WHICH ONE ELECTRICAL CONNECTION IS MADE TO THE SWITCH, AT LEAST ONE OF ONLY THOSE CONTACT FINGERS LOCATED AT THE SAME SIDE OF SAID CYLINDRICAL CONNECTOR MEMBER AS IS LOCATED SAID CONNECTION LUG BEING LONGER THAN THE REMAINING CONTACT FINGERS THEREBY TO SERVE AS THE LAST TO DISENGAGE FROM SAID OTHER MAIN CONTACT MEMBER, AND SAID CYLINDRICAL CONNECTOR MEMBER ALSO INCLUDING AN INVERTED U-SHAPED YOKE OF HIGHLY CONDUCTIVE MATERIAL EMBEDDED THEREIN AT THE SIDE OF WHICH SAID CONNECTION LUG IS LOCATED AND WHICH SURROUNDS SAID LONGER CONTACT FINGER, SAID YOKE SERVING IN PART TO ESTABLISH TWO CLOSELY PARALLEL CURRENT FLOW PATHS OF OPPOSITE DIRECTION BETWEEN SAID CONNECTION LUG AND THE ADJACENT SIDE OF SAID CYLINDRICAL CONNECTOR MEMBER AND SAID OTHER MAIN CONTACT MEMBER SUBSEQUENT TO DISENGAGEMENT OF SAID REMAINING CONTACT FINGERS BUT PRIOR TO DISENGAGEMENT OF SAID LONGER CONTACT FINGER, ONE OF SAID CURRENT FLOW PATHS BEING THROUGH SAID LONGER CONTACT FINGER THEREBY TO ESTABLISH THEREON AN ELECTRODYNAMICALLY DERIVED FORCE ACTING IN A RADIALLY INWARD DIRECTION TO INCREASE THE PRESSURE OF SAID LONGER CONTACT FINGER ON SAID OTHER MAIN CONTACT MEMBER AND THEREAFTER MOVE TO CONTACT DISCONNECTION ARC TOWARD THE CENTER OF SAID NOZZLED TUBULAR CONTACT MEMBER. 